In 2011, St. Bernard was the first municipality in which treated home water pipes tested positive for the Naegleria fowleri amoeba. In that case, tests showed that the parish water system did not itself carry the pathogen.

Both instances were uncovered after deaths from primary amebic meningoencephalitis – commonly known as PAM – which is an infection caused by the amoeba entering the nose that leads to the destruction of brain tissue.

St. Bernard Parish school superintendents, government officials and residents took precautionary measures Thursday and Friday even as CDC and Louisiana Department of Health and Hospitals officials assured residents that the water is safe to drink.

People can't contract the infection by drinking contaminated water, because stomach acid will kill the amoeba, health officials say. Naegleria fowleri infects people by entering the body through the nose.

As an alternative, the school provided hand sanitizers in all its restrooms and classrooms, according to Sarah McDonald with the Archdiocese of New Orleans.

Lynn Oaks School sent a note to parents asking them to be careful in how they discuss the matter as not to cause "widespread panic among our school children."

And at the Breaux Mart grocery store in Chalmette, shoppers bought about double the amount of bottled water compared with a typical day, according to Jared Thomas, the store manager.

Michelle Kamm of Chalmette loaded her van with eight jugs of water outside the Breaux Mart, saying she was buying the water for her husband's gumbo. "He's cooking gumbo for a special event and he doesn't want to answer questions about where the water came from," Kamm said.

When announcing the child’s death, St. Bernard and DHH officials emphasized that tests of the parish water system were continuing, and there was no reason to believe that the amoeba was ever in the parish’s water system.

View full sizeThe Naegleria fowleri pathogen and life cycleCenters for Disease Control and Prevention

In June 2011, a 28-year-old St. Bernard man died from primary amebic meningoencephalitis. He had become infected after using his home’s tap water in a device called a neti pot, which is used to rinse the nasal passages and sinuses to relieve allergies, colds and sinus trouble.

Later in 2011, a 51-year-old DeSoto Parish woman died from the same infection after also using tap water in a neti pot and becoming infected with the deadly amoeba.

Those are the only recorded deaths from the amoeba in Louisiana since 1962, according to the CDC. Nationwide, there have been 132 recorded infections from 1962 through 2013, with only two survivors.

One of those is a 12-year-old Arkansas girl, Kali Hardig, who lived through the infection after being given an experimental drug that the Food and Drug Administration just this year started allowing the CDC to directly provide to patients suffering from such amoeba infections.

Hardig was released from the hospital Thursday, according to the CDC.

Why St. Bernard?

How St. Bernard’s water system and home pipes became contaminated with the rare amoeba remains a mystery.

“What you have got in St. Bernard is a unique event,” said Michael Beach, who is the head of the CDC’s Waterborne Disease Prevention Branch. “We have never seen this before in the United States and so we don’t know as much about it.”

But Beach said the CDC has recently been working with Australian officials because Australia has one of the few other examples of the amoeba in a treated water system. There were several deaths in Australia from the brain infections in the 1970s and ‘80s, but more frequent chlorine treatments apparently killed off the deadly amoeba.

In terms of how it entered the St. Bernard water system, Breach said Friday that “we’ll never know for sure,” but he and others said it often comes through breaks in water system’s pipes.

And as Jake Causey, the administrator who oversees safe drinking water for Louisiana, pointed out Friday, the St. Bernard water system has suffered its hard knocks during the past decade. “The system was severely compromised during Katrina,” said Causey. “There were about 1,000-point repairs for breaks in that system when they were bringing it back online.”

Jacob Groby, St. Bernard government’s superintendent who handles quality control for the parish’s water and sewer division, said the parish system was flushed out with chlorine after Katrina and it currently is going through a similar chlorine flush that should rid the system of the contaminants.

A lesson to be learned

Plaquemines Parish President Billy Nungesser announced Friday afternoon that Plaquemines has put in a request to the state to get its water system tested as well.

“Parish employees will flush our water lines this weekend and we will take every precaution necessary to ensure that the water in Plaquemines Parish is safe for our residents," Nungesser said. "There is no reason to believe that we have a problem with our water. The steps we are taking are purely precautionary measures."

Causey said that the flushing of St. Bernard’s water system – which involves switching from chloramine to pure chlorine, both disinfectants, and increasing the amount of that treated water running through the pipes – likely will last for several weeks.

“And then, at that point, we plan to come back and do some additional tests for the amoeba to send back to CDC for analysis both from the sites that tested positive and from additional areas in the system, to basically cover all of our concerns,” Causey said.

Beach said, “St. Bernard will be a learning lesson.

“Nobody wants to be the first time, but unfortunately St. Bernard is that, and I think this unprecedented incident has made clear that we at the CDC need to begin planning ways to assist other water systems across the country if something similar occurs,” Beach said. “Let’s learn what we can in Louisiana to find some guidance.”